Support is requested for a Keystone Symposia meeting entitled Biology of B Cell Responses, organized by Hedda Wardemann, Michael G. McHeyzer-Williams and Michel C. Nussenzweig. The meeting will be held in Keystone, Colorado from February 9 - 14, 2014. The requirements and processes relevant for the induction of protective B cell responses remain in large unclear and inefficient or deregulated B cell responses are frequently associated with the development of diseases. The goal of the meeting is to deepen our understanding of the factors and mechanisms controlling and regulating B cell development, differentiation and activation under steady-state conditions and in autoimmunity, infection, and B cell tumors. The specific aims are: 1) to identify factors involved in the developmental programming and function of B cells; 2) to elucidate the mechanisms relevant for the establishment and maintenance of B cell self-tolerance; 3) to define how B cell responses are initiated and regulated; 4) to provide insight in the mechanisms and dynamics underlying germinal center responses; 5) to establish the link between immunoglobulin gene diversification and B cell tumor development; and 6) to provide an interactive forum to involve new investigators and highlight their research. The meeting will provide a platform for early stage and established researchers to engage into interactive discussions on all aspects of the biology of B cell responses from B cell evolution to basic principles of B cell biology and human B cell immunology. It will thereby facilitate and booster the exchange of ideas and the initiation of collaborative research on B cells at international level. Interactions will be fostered across disciplines. Access to the parallel meeting on Prophylactic and Therapeutic Antibodies will provide all attendees with the unique opportunity to engage into expanded interdisciplinary interaction with translational scientists from academia and industry.